[sgiitk]

One more trick, if the radiator is not empty - it will be uncomfortable but will help. Switch the cat to full heater with the AC compressor off. The small radiator in the HVAC circuit will help to cool the car somewhat.

[Catalyst_delhi]

When flushing your coolant , get distilled water from the battery shop. this is just pure water and has no acid.(even if the call it battery water).
In a big bucket mix concentrate coolant and water to 50/50 or as per manual. Just gave my cars new coolant , coolant cap and hoses. If you can get the premixed coolant that would be the best bet. I also attach a small magnet in the plastic coolant tank to catch minor rust/metal particles. I did this 100kms before the flush and got small particles stick to the part where the magnet was kept. fyi distilled water is 60 rupees for 5 litres. Ford red coolant is 250 rupees for a litre

[kvish]

There seems to be a problem in my FIAT Adventure. The temperature needle goes to RED in a matter of 4-5 KMs. The engine fan is continuously ON. What confuses me is that it the engine doesn't seem overheated. If I drive on an open stretch the temperature comes down automatically, it shoots up at stop-go traffic. Since the fan is ON at maximum all the time, the battery seems to be draining out. I am not sure where the problem is ? I suspect the radiator not doing its job well (which might explain why the incoming air at higher speeds is cooling things down).

[Pal]

Switch the cat to full heater with the AC compressor off. The small radiator in the HVAC circuit will help to cool the car somewhat.

The Heater Trick:

In either of the above mentioned situations, you can try switching your heater on to drain heat from the engine. Remember, your HVAC sources heat from the engine.

First up - this point is only applicable if reduced coolant qty in the cooling system is the cause of over-heating.

Now, with all due respects, I beg to differ here for 2 reasons:

1) In "Ignition ON" position of Key, the battery is only getting more and more discharged with all the electricals on. There is no alternator drive to recharge it to 12V/24V.

If switched ON in above condition, the cooling fan will quickly sip - off the limited battery power (slurp!). Now imagine the driver doing that over several minutes and voila, you face a new problem of 'vehicle not starting due to low battery voltage'!

2) The HVAC, as correctly pointed out by GTO, has no heating coil but in with the temerature knob in the red indicated zone, small levers/motors open up a separator flap in the ducts to allow mixing of 'hot' air with the ambient / cold air of the cooling system.

So essentially, while the car is standing still due to overheating, the HVAC system with its small blower is only sucking some of the air around the engine bay. Hence cooling rate is going to be marginal (Imagine trying to cooling something with a vacuum cleaner). Compare this with battery power lost due to point 1 and the god-knows-how condition of battery, I seriously think it could be a blunderous decision best left untouched by the lay man!

My advice:
Cooling down of engine bay by ambient wind/breeze will only cost some extra time. So Relax. Chill. And let chill.

[S5157]

Another reason for coolant loss would be a fault in heater core of HVAC. The hot coolant passes through the heater core and if there is a fault or leakage it would drain the coolant and engine will overheat. This could be easily identify in certain cars as you could see coolant leakage inside the cabin. If this happens we could bypass the heater core and refill the radiator with water. Take it to the next accessible service station and fix the heater core.

I was once stranded on a highway in midnight due to engine overheating and the mechanic from the service station 600 kms away guided me over the phone to bypass the heater core. I did it and refilled the radiator with water and I could reach my destination safely.

I am listing the steps to do it below.This should be applicable in most cars.

(Note: I copied the steps from ehow website to ensure that I don't miss anything)

1. Disconnect the heater hoses from the firewall side. Both heater hoses will be connected to nipples, which go through the firewall and into the heater core. To bypass the coolant around the heater core, it is necessary to divert the heater hoses coming from the engine to somewhere other than the core itself. Most of the time the heater hoses are connected with hose clamps that require the use of a flat blade screwdriver, but some companies installed pinch-style clamps, which are squeezed with pliers.


2. Connect the 2 hoses together using small diameter plastic tubing. This step requires you to have the fix on hand in case of an emergency, but if just bypassing the core in your driveway then it can be purchased after the incident. The recommendation is to get small-diameter plastic PVC tubing (the same diameter as the inside of the heater hose). Cut one 3-to-4 inch piece of the tubing and file the ends to ensure they are smooth. Then connect the 2 hoses together and tighten the clamps over the tubing. This will bypass the heater core without impeding cooling effectively. Be advised that the heater and defrost system in the vehicle will no longer work until the heater core is replaced and properly connected again. Auto parts stores also sell heater hose repair kits that come with pre-formed plastic connectors that will work well also.


3. Start the engine and check for leaks. If the heater hoses are connected properly and clamps are tightened down, the system should contain no leaks. Allow the vehicle to reach operating temperature (so that the thermostat is allowed to open) and closely watch the connection points. Feel the hoses to ensure they are getting hot if no leaks are detected. If there is a leak and a slight tightening down the hose clamp doesn't stop it, a small amount of RTV silicone may be used on the plastic connector to help seal the connection. Allow the system to cool before working on any heater hoses.

[dhanushs]

My two cents to this thread.

(i) Probable areas where you should keep checking the temp guage more frequently:

• Steep climbs in very low gears (1st or 2nd)
• Climbing up ghats
• Traffic

Reason: In the first two cases, the engine works really hard, hence it overheats, in the third case, there is very little ram air to cool the engine.

(ii) If the needle has moved to the dangerous territory, but you are yet to see the classic symptoms like loss of power, etc.. My suggestion would be to STOP but DO NOT turn off the engine. idle it. Also, idle the engine, and driving down an incline will help matters a LOT.

Reason: A running engine keeps the oil and coolant in circulation which helps cooling down things faster. However: If you still see the temperature rising (Reason: No coolant, blocked plumbing, malfunctioning thermostat valve etc..) stop the engine IMMEDIATELY.

(iii) Sometimes, stones or debris hit radiator, and damage its fins, which in turn will result in loss of coolant, and hence overheating. A get-home-tip in case of such a situation is: Identify where the leak is in the radiator. Take a plier and block that particular pipe and seal it with M-Seal. Cooling efficiency will drop drastically, but will get you home nevertheless.

(iv) If you desperately need to drive with an overheated engine. The most important thing is to NOT LUG the engine. Also, as take as much care to NOT REVV the engine higher than required. Do not operate any electricals, as it will put additional load on the engine.

IMO, overheating is the worst nightmare a car lover could ever face. It is also one of the few issues which, if you keep a vigilant eye, can come out unscathed. So, please take a glance at the instrument console frequently. It will save you your car.

Also, attaching a flow chart, which I believe is apt for this thread.

[Catalyst_delhi]

Originally Posted by kvish

There seems to be a problem in my FIAT Adventure. The temperature needle goes to RED in a matter of 4-5 KMs. The engine fan is continuously ON. What confuses me is that it the engine doesn't seem overheated. If I drive on an open stretch the temperature comes down automatically, it shoots up at stop-go traffic. Since the fan is ON at maximum all the time, the battery seems to be draining out. I am not sure where the problem is ? I suspect the radiator not doing its job well (which might explain why the incoming air at higher speeds is cooling things down).

You have a weak water pump. Change the water pump , change the radiator/coolant bottle cap and flush coolant.

[naveenp]

Dear GTO,

"First things first:

The first thing you should do is switch the air-conditioner off, "

Not sure about other cars, but with my Palio MJD, the second fan kicks in only when the AC is switched on. So whenever i am driving uphill or in heavy traffic, i prefer switching on the A/C to keep the temperature down.
I hope i am not doing anything incorrect here.

Regards
Naveen

[sandeepmohan]

Originally Posted by kvish

There seems to be a problem in my FIAT Adventure. The temperature needle goes to RED in a matter of 4-5 KMs. .

Mayte, you might want to stop driving the car and get the cooling system checked before you wreak the engine and fixing this engine will cost you an arm and leg. Before the arm and leg goes, you will first have to touch Fiat on its feet for parts. Is there any coolant at all in the tank? Please don't wait for signs of steam. It will be too late.

[sandeepmohan]

Originally Posted by naveenp

Not sure about other cars, but with my Palio MJD, the second fan kicks in only when the AC is switched on. So whenever i am driving uphill or in heavy traffic, i prefer switching on the A/C to keep the temperature down.

There is only fan unit in the Palio with two speeds on it. You don't have to turn on the AC for the fan to start up. The ecu will trigger the fan when it senses the requirement for cooling the engine/cooling system. If the fan is not starting up, it could be a failed sensor or even the slow speed function of the fan that has failed. Low speed fan is activated automatically in the Palio and pretty much all modern cars when you don't have the AC running.

What you are doing is not required at all.

[kvish]

Thanks Sandeep, Catalyst_Delhi for your suggestions. I am visiting the mechanic tomorrow.

[directinjection]

Originally Posted by naveenp

Not sure about other cars, but with my Palio MJD, the second fan kicks in only when the AC is switched on. So whenever i am driving uphill or in heavy traffic, i prefer switching on the A/C to keep the temperature down.
I hope i am not doing anything incorrect here. Regards
Naveen

Palio has only one fan. When you switch on the AC, the fan starts rotating at higher speed and hence, as a by-product, the engine temperature also comes down faster.

Originally Posted by sandeepmohan

in the Palio ...... If the fan is not starting up, it could be a failed sensor or even the slow speed function of the fan that has failed. Low speed fan is activated automatically in the Palio and pretty much all modern cars when you don't have the AC running.

The fan may also fail because of problem in the fan relay switch. Happened with my Palio Stile only last week. Temp. shot up and coolant was also lost.

Originally Posted by sandeepmohan

What you are doing is not required at all.

Even I tried the technique of switching on the AC to cool the engine but it didn't help. Temp. kept on going up. I had to stop the car when the temp. gauge almost reached the "H" sign. Opened the bonnet, allowed the engine to cool down. Fan wasn't working after first turn of key although it should have because of high temperature. After the engine had cooled down, I opened the coolant cover after 20-30 minutes. It had become less. I poured more than 1 litre of water only since no coolant shop was around. When the temp. needle had come down to the first mark (about 20%), I turned on the engine & switched on the AC. The fan didn't start. I turned the AC off, switched on the heater and voila, the problem was resolved! I drove nearly 25 KMs after that (with heater on) and the temp. gauge hardly went above 25%.

I took the car to the workshop and they identified the problem as a failed relay switch which was replaced. Now fan is working normally although the temp. remains a little higher than earlier because of (I suspect) incorrect water-coolant ratio that resulted from pouring only water into the coolant tank.

Originally Posted by kvish

There seems to be a problem in my FIAT Adventure. The temperature needle goes to RED in a matter of 4-5 KMs. The engine fan is continuously ON. What confuses me is that it the engine doesn't seem overheated. If I drive on an open stretch the temperature comes down automatically, it shoots up at stop-go traffic. Since the fan is ON at maximum all the time, the battery seems to be draining out. I am not sure where the problem is ? I suspect the radiator not doing its job well (which might explain why the incoming air at higher speeds is cooling things down).

Yes, even I think the problem is with your radiator. How many KMs has your car covered? In fact, my Advy (which has crossed 90,000 KMs) has also started showing early signs of this problem although it never goes close to red. I'll get it checked closer to summers!

[ramzsys]

Originally Posted by Catalyst_delhi

You have a weak water pump. Change the water pump , change the radiator/coolant bottle cap and flush coolant.

Catalyst, another possibility is that maybe his thermostat is stuck?

[Catalyst_delhi]

Originally Posted by ramzsys

Catalyst, another possibility is that maybe his thermostat is stuck?

Could be but i think he reported it is the fan relay which went

[d_himan]

A year back, when my friend's car overheated,

1. The car was accelerating a bit jerkily.

2. He also had to rev higher to go fast.

Both of us didn't notice anything until some passer-bys pointed out to steam rising from the bonnet! The temperature was at H.

A mechanic nearby diagnosed it as a stuck thermostat valve, removed it, put some distilled water.

It's been a year now and the thermostat has not been replaced.

Is it OK to not replace the thermostat if driving is done only in hot climes? The Fuel Efficiency and the time taken to reach the engine operating temperature are also similar to the way they were earlier and he's quite happy